Log break-down method and apparatus

ABSTRACT

Method and apparatus for breaking down logs in a continuous or substantially continuous manner into useful products, such as pulp chips, boards and/or timbers. The method entails conveying each log past a set of cutting elements arranged to cut one or two flat horizontal surfaces thereon. It preferably includes placing the cut log with the flat surface or surfaces on a suitable conveyor, and moving the log past a second set of cutting elements arranged to repeat the original cutting operation. The method preferably includes removing slab areas of the logs as pulp chips while simultaneously removing boards therefrom during formation of the flat areas at each set of cutting elements. The apparatus is designed to carry out part or all of said method. The apparatus grips each log from below and moves it horizontally past said first set of cutting elements arranged above the log, and it preferably includes a second stage wherein the log after being turned over is transported past said second set of cutting elements arranged above the turned log.

United States Patent [72] Inventors Arie Bos Ladysmith, British Columbia, Canada; Ronald L. Greenough, Tomasville, Ala. [211 App]. No. 733,181 [22] Filed May 29, 1968 [45] Patented Jan. 5, 1971 [73] Assignee MacMillan Bloedel Limited Yancouver, British Columbia, Canada [54] L06 BREAK-DOWN METHOD AND APPARATUS 28 Claims, 14 Drawing Figs.

[52] U.S. Cl. 144/312, 143/22, 144/3, 144/326 [51] Int. Cl. B27b H00 [50] Field ofSearch 143/22, 38; 144/3, 3-l4, 41, 309, 312, 321, 323, 326,116, 172, 162

[56] References Cited UNITED STATES PATENTS 1,938,108 12/1933 Morris 144/116 3,259,157 7/1966 Runnion... 144/41 3,304,971 2/1967 Pease 144/3 3,313,329 4/1967 Mitten 144/312 3,318,347 5/1967 Alich 143/22 3,457,978 7/1969 Ahlstedt 144/312 Primary Examiner-Gerald A. Dost Attorney-Fetherstonhaugh & Co.

ABSTRACT: Method and apparatus for breaking down logs in a continuous or substantially continuous manner into useful products, such as pulp chips, boards and/or timbers. The method entails conveying each log past a set of cutting elements arranged to cut one or two flat horizontal surfaces thereon. lt preferably includes placing the cut log with the flat surface or surfaces on a suitable conveyor, and moving the log past a second set of cutting elements arranged to repeat the original cutting operation. The method preferably includes removing slab areas of the logs as pulp chips while simultaneously removing boards therefrom during formation of the flat areas at each set of cutting elements.

The apparatus is designed to carry out part or all of said method. The apparatus grips each log from below and moves it horizontally past said first set of cutting elements arranged above the log, and it preferably includes a second stage wherein the log after being turned over is transported past said second set of cutting elements arranged above the turned log.

PATENTEU JAN 5 IBYI 3552.457 SHEET 3 OF 3 I This invention relates to a method and apparatus for breaking down logs in a rapid and continuous or substantially continuous rnanner into boards while, if desired, simultaneously converting the slab areas of the logs into pulp wood chips.

The breakdown of a log in a standard sawmill commences at a head saw. The usual practice is to place the log on a standard l o sawmill carriage which grips the log along the top and bottom surfaces thereof from a side edge. The log is shifted transverf sely of the carriage until its opposite edge projects from the carriage side so that when the carriage moves past the head i saw, the latter cuts the log in a longitudinal direction. Because of the way the log is gripped on the carriage, it is possible to out only one side of the log' during each trip past the saw. The

carriage is moved past thesaw to cut off a slab and leave a-flat surface. When the carriage is back and clear of the saw after each pass, the log is turned on to its flat surface. Thus, the log must be moved past the saw at least four times in order to produce a squared-timber, and many more times if boards are cut off as well as the slab material. This greatly limits the number of logs that can be handled at the head saw in a given time, and if the mill has only one head saw, this limits the speed of the entire operation of 'the mill. Another disadvantage is that the carriage is stationary while a log is being placed thereon and first gripped by the gripping dogs and while the resulting timber is being removed therefrom, so that? no cutting takes place during these times. The standard carwaste of time during the backstroke of the carriage, although some mills use band sawswith cutting teeth on both edges thereof so that cutting can take place each time the carriage moves past .the saw in'either direction. The standard sawmill another side area thereof can be cut. Furthermore, the slabshave to be conveyed away from'the sawing apparatus and either burned or converted into chips to be used in the pulp industry. This necessitates additional handling of the slabs, machineryfor converting them into chips, and theuse of floor space-in the mill. Furthermore, the chipping of slabs usually results in chips of inferior grade.

SUMMARY OF THE INVENTION The method of breaking down logs according to this invention comprises gripping the log from beneath, moving it longitudinally past a plurality of cutting elements. Although different single cutting elements may be employed, in the preferred form of the invention, these cutting elements are arranged in pairs, the elements of each pair being located at right angles to each other and positioned so as to cut along the,

I top of the log. Usually slab portions of the log and at least two boards are simultaneously removed from the log to leave it with two flat surfaces extending longitudinally thereof at sub, stantially right angles to each other, and any suitable cutting elements may be used for this purpose. It is preferred to remove the slab portions as pulp chips by means of chipper heads arranged at right angles to each other. Immediately following the chipper heads the log is preferably subjected to the action of two head saws arranged at right angles to each other and spaced inwardly towards the longitudinal centerline of the log from the operational planes of the chipper heads. If desired, a log can be subjected to the action of a second pair of head sawsarranged at right angles to-each other and spaced.

inwardly from the planes of the first pair of head saws. Furthermore, only one chipper head and one head saw may be used, in which case, they preferably would be arranged to cut in substantially horizontal planes.

In the preferred fonn of the invention, the method is continued by moving the log on a suitable conveyor past a second set of cutting elements which remove slab material and cut one or more boards forwardly These cutting elements are arranged in the same manner as the first set of cutting elements and preferably consist of chipper heads and head saws arranged at right angles to each other and to the previously-cut pair of flat surfaces of the log. This operation results in a squared timber.

The invention also contemplates apparatus for carrying out the above-described method. This apparatus includes carriage means for gripping logs from beneath. This carriage means or apparatus can be reciprocated in the usual manner, but preferably is moved forwardly along an endless track, or set up -'in a's eries or an endless chain which always moves in one direction.

One or more logs are carried by this apparatus at a time, and with the continuously moving embodiment, logs are continuously removed therefrom and placed thereon without stopping the apparatus so that when a log is being positioned on the carriage apparatus, another one thereon is being cut. Another great advantage of the present apparatus is that each log is gripped from beneath so that two or more cutting elements can be working on the log at a time. For example, angularlyarranged head saws are placed at right angles to each other so as to cut two slabs or boards off the log at the same time from riages are reciprocated pastthe saw, and usually represents a the upper surface thereof. Actually, a plurality of pairs of saws can be positioned along the path of movement of the log so that two, four or more boards can be cut therefrom at substan- I remove the slab material as pulp chips while two or more boards are substantially simultaneously being cut from the log. This operation leaves two flat surfaces on the log extending at right angles to each other. The invention also contemplates conveying apparatus, such as conveying rolls arranged in a V relative to each other, upon which the previously-cut log is placed with its flat surfaces resting on said conveying apparatus. This conveying apparatus directs the log past a plurality of cutting elements in a second cutting stage which are the same as those of the first cutting stage of the apparatus. At the: second stage the remaining slab material is removed, preferably as chips, and a plurality of boards are cut from the log, leaving a squared timber. Thus, the log is broken down in two stages, one immediately following the other without any waiting for loading and unloading operations, or one cutting operation delaying the other.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 5 are diagrammatic cross sections through a log handled in accordance with the present method and by the present apparatus;

FIG. 6 is a diagrammatic cross section of a log, showing the various cuts to which it is subjected during the first stage of this method, diagrammatically paratus used;

FIG. 7 is a diagrammatic view similar to FIG. 6, showing the various cuts and some of the apparatus used during the second stage;

FIG. 8 is a diagrammatic side elevation of the apparatus of the first stage;

FIG. 9 is a diagrammatic plan view of the apparatus of the second stage;

'FIG. 10 is a side elevation of the first stage apparatus;

FIG. 11 is a vertical section taken on the line 1 1-11 of FIG. 10, showing chipper heads of the cutting elements;

FIG. 12 is a vertical section taken on line 12-12 of FIG. 10,

, showing small edge trimmer heads;

FIG. 13 is a vertical section taken on the line 1343 of FIG. 10, showing the head saws of the cutting elements; and

illustrating part of the ap- FIG. 14 is a cross section similar to FIG. 11, but illustrating an alternative form of chipper and cutting elements.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, FIGS. 1 to 5 illustrate the results when a log is dealt with according to the present method. FIG. 1 shows log after it has passed a pair of chipper heads of the first cutting stage, said heads having removed two slab areas of the log thereby leaving flat longitudinal surfaces 12 and 13 which extend substantially at right angles to each other. It is preferable, although not absolutely necessary, to use a cutter head to cut a longitudinally-extending notch 15 in the part 16 of the log between surfaces 12 and 13, see FIG. 2. This notch is V-shaped in cross section so that side surface 18 thereof is substantially parallel with surface 12, and side surface 19 of the notch is substantially parallel with and spaced inwardly from surface 13. The depth of notch 15 is adjusted in accordance with the thickness of the first two boards to be cut off the log, said boards being defined by broken lines 21 and 22 in FIG. 2. It is preferable, although not absolutely necessary, to cut notches 25 and 26 in opposite sides of the log with their respective surfaces 28 and 29 aligned with notch surfaces 18 and 19, respectively.

FIG. 3' illustrates log 10 after boards 21 and 22 have been cut therefrom, leaving surfaces 31 and 32 extending at right angles to each other and joining at apex 33. Thus, the slab material of the log has been removed as pulp chips down to surfaces 12 and 13, and then boards 21 and 22 have been removed to leave the partially formed timber 35 of FIG. 3 said boards being formed with substantially parallel opposite faces.

It is preferable further to treat timber 35 in a second cutting stage in accordance with the present process. The timber is turned over so that surfaces 31 and 32 thereof are facing downwardly, and these are placed against suitable moving means for moving the log past a second set of chipper heads which remove the remaining slab portions (shown in broken lines) of the log down to surfaces 38 and 39 lying substantially at right angles to each other, see FIG. 4. If desired, a V-shaped notch 40 may be cut between these surfaces for the same purpose as-notch 15 described above. Then the log is continued and moved past saws arranged at right angles to each other to remove boards 42and 43 having opposite substantially parallel faces and leaving flat surfaces 44 and 45 extending at right angles to each other and meeting at apex 46, thus completing the formation of squared timber 48, see FIG. 5.

FIG. 6 diagrammatically illustrates cutter and saw elements ofa machine for carrying out this process. For the sake of convenience, these elements are shown in one plane, but it will be understood that they will be in different successive planes relative to the direction ofmovement oflog 10.

As log 10 is moved along a predetermined path, it is moved past a pair of chipper heads 52 and 53 arranged substantially at right angles to each other and positioned relative to the log so that they remove slab material 55 and 56 in the form of pulp chips to form surfaces 12 and 13 on the log referred to above,

These heads are adjustable towards and away from the longitudinal center 57 of the log so that the thickness of slab material to be removed can be adjusted. Heads of this type are on the market, and do not need any further description herein. A cutter head 60 is located above the level of chipper heads 5-2 and 53, said head 60 having a V-shaped periphery which cuts into the log between the chipper heads to form V-shaped notch 15. A pair of side cutters 63 and 64 are located so that they cut V-shaped notches 25 and 26 in the log spaced inwardly from faces 12 and 13. Cutter heads 60, 63 and 64 are mounted for movement inwardly and outwardly relative to the log in order to accommodate logs of different sizes.

A pair ofsaws 66 and 67 are positioned along the path of log 10. In this example, saws 66 and 67 are hand saws and have band blades 68 and 69 respectively positioned at right angles to each other and spaced inwardly of the log relative to chipper heads 52 and 53. The blades of these saws cut off boards 21 and 22 and leave flat surfaces 31 and 32. Saws 66 and 67 are mounted for adjustment towards and away from the center of the log.

FIGS. 6 to 13 more or less diagrammatically illustrate apparatus 75 for completely breaking down .logs into useful products. Apparatus 75 includes a first breakdown stage or section 77, shown in FIG. 8, and a second breakdown stage or section 79, see FIG. 9.

FIGS. 8 and 10 to 13 illustrate the first breakdown section 77. This section includes any suitable log transporting means, and in this example the transporting means is an endless log transporting unit 84 made up of a plurality of individual carriers 85 which are interconnected by a chain 86 and move forwardly through the apparatus on tracks 87. Each carrier 85 has wheels 88 riding on tracks 87. Tracks 87' have downwardly-curved sections 90 and 91 at opposite ends, and lower track 92 extending parallel to said tracks 87 has curved ends 93 and 94 spaced outwardly from curved sections 90 and 91 so that when carriers 85 move around section 90, the wheels thereof are picked up by end 93 to direct the carriage which is being turned upside down to ride on lower tracks 92. At the opposite end, the carriages ride up end 94 and transfer on to the curved section 91 of tracks 87. Chain 86 runs around large sprockets 96 and 97 at the ends of these tracks, and one or both of these sprockets are driven by a source of power, not shown, to cause the carriers to move through apparatus section 77 in the direction of arrow 98.

Each carrier 85 include includes a base 102, a laterally shiftable support 103 on the base, and a vertically adjustable standard 104 carried by support 103, see FIG. 11. The upper end 106 of standard 104 is V-shaped to receive a log 10, and the standard includes power operated dogs 107 and 108 adapted to dig into the lower surface of the log supported by the standard to retailog thereon. The construction and'operation of these dogs form part of a separate invention, and do not need further description herein.

Each log 10 is made ready for apparatus section 77 by standard apparatus and technique. As the conveyor for this section is endless, log 10 is fed on to carriers 85 at one end of the conveying apparatus without stopping the latter, driven rolls 112 being illustrated for this purpose in FIG. 8. The front end of the log is fed on to a carrier 85 and the dogs 107 and 108 thereon are operated to grip the undersurface of the log. As each succeeding carrier 85 moves up under the log, its dogs are operated to grip it.

The carriers move the log along a predetermined path through breakdown section 77. It first encounters chipper heads 52 and 53 which are mounted respectively on shafts 115 and 116 which project from electric or hydraulic motors 117 and 118 which are slidably mounted on inclined supports I20 and 121. Heads 52 and 53 are movable towards and away from the longitudinal center of the path along which logs 10 are moved so as to accommodate logs of different sizes and to remove as chips different thicknesses of slab material from each log. These heads are shifted by a standard set-works, not shown, which are well known in the lumber industry.

Cutter heads 63 and 64 are supported along the log path, each just behind the chipper head, said cutter heads being driven by motors 123 and 124. Cutter head 60 is mounted at the top of the path and positioned to cut V-shaped notch 15 in the log along the top surface thereof. Head 60 is driven by motor 126. Cutter heads 60, 63 and 64 are adjustable towards and away from the longitudinal center of the log path by standard mechanisms which have been omitted from the drawings for the sake of clarity.

Saws 66 and 67 are mounted on opposite sides of the log path so that their blades 68 and 69 are inclined at right angles to each other. Saws 66 and 67 are mounted on suitable supports I30 and 131 and are adjustable by standard set-works, not shown, towards and away from the center of the log path. Saw 66 is driven by electric motor 133, while saw 67 is driven by motor 134.

As each log is moved through breakdown section 77 of f the apparatus by carriers 85, heads 52 and 53 remove a predetermined amount of slab material as pulp chips. These are directed out of the apparatus by chutes 137 and 138, see

' FIG. 11. Notches 15,25 and 26 are cut in the log by cutters The apparatus described so fartreats log 10 in the manner illustrated in FIGS. 1 to 3 and 6, and then the log is turned results illustrated in FIGS. 4 and 5.

Log 10 is turned over either manually or by suitable known equipment and directed into a suitable conveyor, indicated by rollersl45 and 146. This is a known type of conveyor in which the rollers are arranged .in a-V, as clearly shown in FIG. 7. The upper driving elements have been omitted for the sake of clarity. Flat'surfaces 31 and 32 of log 10 rest on rollers 145 and 146. The log in this second stage is moved past successive cutting elements to form flat surfaces 38 and 39 lying at right angles to each other and to flat surfaces 31 and 32. In this example, slab material is removed as pulp chips and two boards are cut off by a pair of chipper heads 148 and 149, a central chipper head 150, side chipper heads 152 and 153 and head saws 155 and 156. The cutting elements are adjustably mounted in the second stage 79 of the apparatus in the same manner as the corresponding elements in the first stage section 77.

Referring to FIG. 7, the slab portions 160 and 161 of log 10 are removed as pulp chips by chipper heads I48 and 149, and

boards 42 and 43 are removed by head saws 155 and 156. This results in the squared timber 48 of FIG. 5.

Transporting unit 84 'ispreferably of the continuous type shown in FIG. 8 so that logs can be continually loaded thereon while other logs are passing through the first cutting stage, and while partially squared logs are being removed therefrom. The partially squared logs are moved on to V-shaped moving means of the second cutting stage so that the logs are continuously converted into the squared timbers. This is considered to be the ideal way, but it is to be understood that the conveying means of both the first and second stages may be reciprocating elements. In. this case, the advantages ofthe continuous operation would be lost, but two slab portions and two boards would be removed from a log each time it is moved past the successive cutting elements.

Although the method and apparatus of this invention is primarily concerned with removing two slab portions and at least two'boards from each log as it passes thecuttiri g elements, the invention also contemplates the removal of one slab portion and one board in substantially horizontal planes during each movement past the cutting elements, and apparatus for accomplishing this is diagrammatically illustrated in FIG. 14. Log 170 is mounted on suitable carriage means 171 which may travel around an endless path or may be reciprocated past cutting elements which comprise a vertically-arranged chipper unit 173 having a substantially horizontal chipper head I74 arranged in a substantially horizontal plane above the path of movement of the log. A

plane spaced inwardly towards the log center relative to head manner, which comprises gripping a log from beneath and moving said log past a first set of cutting elements arranged to. out two flat longitudinal surfaces on an upper surface thereof substantially at right angles to each other, said cutting elements removing slab portions of the log and boards therefrom.

2. The method as claimed in claim 1 in which the slab portions are removed as pulp chips.

3. The method as claimed in claim 1 in which the log with the two flat surfaces formed thereon is moved past a second set of cutting elements arranged to cut two longitudinal fiat surfaces thereon substantially at right angles to each other and to the two first-cut surfaces, said second set of cutting elements removing remaining slab portions of the log and boards therefrom.

4. The method as claimed in claim 3 in which the log after passing the first set of cutting elements is turned over and placed on a suitable conveyor, and the second two flat surfaces are fonned along an upper surface thereof, resulting in a squared timber. v

5. The method as claimed in claim 3 in which the remaining slab portions of the log are removed by the second set of cutting elements as pulp chips.

6. A method of breaking down a log in the manufacture of useful products, which comprises gripping a log along one side thereof and moving the log past a pair of chipper heads arranged to remove slab areas of the log as chips leaving two longitudinally-extending flat surfaces substantially at right angles to each other transversely of the log, and continuing the movement of the log past a pair of saws arranged at right angles to each other and positioned substantially parallel with and spaced inwardly from said flat surfaces to out two boards off the log, leaving a partially formed timber with normally-extending second flat surfaces.

7. A method as claimed in claim 6 including moving said log before it reaches said saws past chipper heads shaped and positioned to remove chips from the log to provide finished edges at side edges of said second flat surfaces.

8-. A method as claimed in claim 6 including placing said partially formed timber with said second flat surfaces on moving means and moving the timber past a second pair of chipper heads arranged to remove remaining slab areas thereof as chips leaving third flat surfaces substantially at right angles to each other and to said second flat surfaces, and continuing said movement of the log past a second pair of saws arranged at right angles to each other and positioned substantially parallel with and spaced inwardly from said third flat surfaces to out two more boards off the log, leaving a squared timber with fourth flat surfaces extending substantially neutral to each other and to said second flat surfaces.

9. A method as claimed in claim 8 including moving said log past chipper heads shaped and positioned around the surface of the log to remove chips from the log and provide finished edges at side edges of each of said second and fourth flat surhead saw I75 is adjustably mounted in any desired manner so that its cutting blade 176 lies in'a substantially horizontal faces.

10. A method as claimed in claim 8 in which the log is supported from beneath when moving past the first chipper heads and the first saws.

11. Apparatus for breaking down logs in a continuous manner, comprising a first set of cutting elements, conveying means for gripping a log from beneath and moving it past said cutting elements, said cutting elements being adapted to cut two flat longitudinal surfaces along an upper surface of the log and lying substantially at right angles to each other, said cutting elements simultaneously removing slab portions of the log and boards therefrom.

12. Apparatus as claimed in claim 11 in which said first set of cutting elements includes chipper heads positioned to remove slab portions of the log as pulp chips.

I3. Apparatus as claimed in claim 11 including a second set of cutting elements, conveying means for accommodating the two fiat surfaces of the log and moving the latter past the second set of cutting elements, said latter elements adapted to cut two flat longitudinal surfaces along an upper surface of the log and lying substantially at right angles to each other and to the first-cut flat surfaces, said second set of cutting elements removing remaining slab portions of; the log and boards therefrom.

14. Apparatus as claimed in claim 13 in which said second set of cutting elements includes chipper heads arranged to remove said remaining slab portions as pulp chips.

15. Apparatus as claimed in claim 11 in which said cutting elements are arranged to cut in planes extending at substantially 45 to the horizontal.

16. Apparatus for breaking down a log into useful products, comprising carriage means for gripping a log along one side thereof and moving said log in a longitudinal direction along a predetermined path, a pair of chipper heads arranged relative to said path and shaped to remove slab areas of the log moving past the heads and to leave two longitudinally-extending flat surfaces substantially at right angles to each other transversely of the log, a pair of saws arranged relative to the path and at right angles to each other and positioned in planes substantially parallel with and spaced inwardly of the planes of said flat surfaces to cut two boards off the log as said log moves along the path, thereby leaving a partially formed timber with normally-extending second fiat surfaces.

17. Apparatus as claimed in claim 16 including a single chipper head positioned relative to said pair of chipper heads and the path to remove chips from the log and provide finished edges at adjoining side edges of said second flat surfaces.

18. Apparatus as claimed in claim 17 including additional chipper heads positioned relative to said pair of chipper heads and the path to remove chips from the log and provide finished edges at the opposite side edges of said second fiat surfaces.

19. Apparatus as claimed in claim 16 in which said chipper heads are mounted for adjustment towards and away from the respective planes of the pair of saws.

20. Apparatus as claimed in claim 18 including moving means for receiving said partially formed timber with said second flat surfaces resting on said moving means to continue movement of the log along said path, a second pair of chipper heads arranged'relative to the path and said moving means to remove remaining slab areas of the timber as chips leaving third flat surfaces substantially at right angles to each other and to said second flat surfaces, and a second pair of saws arranged at right angles to each other and positioned in planes substantially parallel with and spaced inwardly from said third fiat surfaces to cut two more boards off the log, leaving a squared timber with fourth flat surfaces extending substantially normal to each other and to said second flat surfaces.

21. Apparatus as claimed in claim 20 including chipper heads around the path along which the carriage means moves and shaped and positioned to remove chips from the log and to provide finished edges atside edges of said second and fourth fiat surfaces.

22. Apparatus as claimed in claim 20 in which said second pair of chipper heads are mounted for adjustment towards and away from the respective planes of second pair of saws.

23, Apparatus as claimed in claim 16 in which said cutting elements are arranged to cut in planes extending at substantially 45 to the horizontal.

24. The method of breaking down logs in a continuous manner, which comprises moving a log past a first set of cutting elements arranged to cut two flat longitudinal surfaces thereon substantially at right angles to each other, said cutting elements during said movement simultaneously removing two slab portions of the log and two boards therefrom along two pairs of parallel planes with the planes of one pair extending substantially at right angles to the planes of the other pair, whereby the boards are formed with substantially parallel opposite faces.

25. The method as claimed in claim 24 in which the log with the two flat surfaces formed thereon is moved past a second set of cutting elements arranged to cut two longitudinal fiat surfaces thereon substantially at right angles to each other and to the two first-cut surfaces, said second set of cutting elements during said second movement removing remaining slab portions of the log and boards therefrom along parallel planes, whereby the last-mentioned boards are formed with substantially arallel opposite faces.

2 e method as claimed in claim 25 in which the log after passing the first set of cutting elements is turned over and placed on a suitable conveyor, and the second two flat surfaces are formed along an upper surface thereof, resulting in a squared timber.

27. The method as claimed in claim 25 in which the'log after passing the first set of cutting elements is turned over and placed on a suitable conveyor, the second two flat surfaces are formed along an upper surface thereof, resulting in a squared timber, and each of said planes extends at substantially 45 to the horizontal.

28. The method as claimed in claim 25 in which all of the slab portions of the log are removed by said cutting elements as pulp chips. 

1. The method of breaking down logs in a continuous manner, which comprises gripping a log from beneath and moving said log past a first set of cutting elements arranged to cut two flat longitudinal surfaces on an upper surface thereof substantially at right angles to each other, said cutting elements removing slab portions of the log and boards therefrom.
 2. The method as claimed in claim 1 in which the slab portions are removed as pulp chips.
 3. The method as claimed in claim 1 in which the log with the two flat surfaces formed thereon is moved past a second set of cutting elements arranged to cut two longitudinal flat surfaces thereon substantially at right angles to each other and to the two first-cut surfaces, said second set of cutting elements removing remaining slab portions of the log and boards therefrom.
 4. The method as claimed in claim 3 in which the log after passing the first set of cutting elements is turned over and placed on a suitable conveyor, and the second two flat surfaces are formed along an upper surface thereof, resulting in a squared timber.
 5. The method as claimed in claim 3 in which the remaining slab portions of the log are removed by the second set of cutting elements as pulp chips.
 6. A method of breaking down a log in the manufacture of useful products, which comprises gripping a log along one side thereof and moving the log past a pair of chipper heads arranged to remove slab areas of the log as chips leaving two longitudinally-extending flat surfaces substantially at right angles to each other transversely of the log, and continuing the movement of the log past a pair of saws arranged at right angles to each other and positioned substantially parallel with and spaced inwarDly from said flat surfaces to cut two boards off the log, leaving a partially formed timber with normally-extending second flat surfaces.
 7. A method as claimed in claim 6 including moving said log before it reaches said saws past chipper heads shaped and positioned to remove chips from the log to provide finished edges at side edges of said second flat surfaces.
 8. A method as claimed in claim 6 including placing said partially formed timber with said second flat surfaces on moving means and moving the timber past a second pair of chipper heads arranged to remove remaining slab areas thereof as chips leaving third flat surfaces substantially at right angles to each other and to said second flat surfaces, and continuing said movement of the log past a second pair of saws arranged at right angles to each other and positioned substantially parallel with and spaced inwardly from said third flat surfaces to cut two more boards off the log, leaving a squared timber with fourth flat surfaces extending substantially normal to each other and to said second flat surfaces.
 9. A method as claimed in claim 8 including moving said log past chipper heads shaped and positioned around the surface of the log to remove chips from the log and provide finished edges at side edges of each of said second and fourth flat surfaces.
 10. A method as claimed in claim 8 in which the log is supported from beneath when moving past the first chipper heads and the first saws.
 11. Apparatus for breaking down logs in a continuous manner, comprising a first set of cutting elements, conveying means for gripping a log from beneath and moving it past said cutting elements, said cutting elements being adapted to cut two flat longitudinal surfaces along an upper surface of the log and lying substantially at right angles to each other, said cutting elements simultaneously removing slab portions of the log and boards therefrom.
 12. Apparatus as claimed in claim 11 in which said first set of cutting elements includes chipper heads positioned to remove slab portions of the log as pulp chips.
 13. Apparatus as claimed in claim 11 including a second set of cutting elements, conveying means for accommodating the two flat surfaces of the log and moving the latter past the second set of cutting elements, said latter elements adapted to cut two flat longitudinal surfaces along an upper surface of the log and lying substantially at right angles to each other and to the first-cut flat surfaces, said second set of cutting elements removing remaining slab portions of the log and boards therefrom.
 14. Apparatus as claimed in claim 13 in which said second set of cutting elements includes chipper heads arranged to remove said remaining slab portions as pulp chips.
 15. Apparatus as claimed in claim 11 in which said cutting elements are arranged to cut in planes extending at substantially 45* to the horizontal.
 16. Apparatus for breaking down a log into useful products, comprising carriage means for gripping a log along one side thereof and moving said log in a longitudinal direction along a predetermined path, a pair of chipper heads arranged relative to said path and shaped to remove slab areas of the log moving past the heads and to leave two longitudinally-extending flat surfaces substantially at right angles to each other transversely of the log, a pair of saws arranged relative to the path and at right angles to each other and positioned in planes substantially parallel with and spaced inwardly of the planes of said flat surfaces to cut two boards off the log as said log moves along the path, thereby leaving a partially formed timber with normally-extending second flat surfaces.
 17. Apparatus as claimed in claim 16 including a single chipper head positioned relative to said pair of chipper heads and the path to remove chips from the log and provide finished edges at adjoining side edges of said second flat surfaces.
 18. Apparatus as claimed in claim 17 including additional chipper heads Positioned relative to said pair of chipper heads and the path to remove chips from the log and provide finished edges at the opposite side edges of said second flat surfaces.
 19. Apparatus as claimed in claim 16 in which said chipper heads are mounted for adjustment towards and away from the respective planes of the pair of saws.
 20. Apparatus as claimed in claim 18 including moving means for receiving said partially formed timber with said second flat surfaces resting on said moving means to continue movement of the log along said path, a second pair of chipper heads arranged relative to the path and said moving means to remove remaining slab areas of the timber as chips leaving third flat surfaces substantially at right angles to each other and to said second flat surfaces, and a second pair of saws arranged at right angles to each other and positioned in planes substantially parallel with and spaced inwardly from said third flat surfaces to cut two more boards off the log, leaving a squared timber with fourth flat surfaces extending substantially normal to each other and to said second flat surfaces.
 21. Apparatus as claimed in claim 20 including chipper heads around the path along which the carriage means moves and shaped and positioned to remove chips from the log and to provide finished edges at side edges of said second and fourth flat surfaces.
 22. Apparatus as claimed in claim 20 in which said second pair of chipper heads are mounted for adjustment towards and away from the respective planes of second pair of saws.
 23. Apparatus as claimed in claim 16 in which said cutting elements are arranged to cut in planes extending at substantially 45 to the horizontal.
 24. The method of breaking down logs in a continuous manner, which comprises moving a log past a first set of cutting elements arranged to cut two flat longitudinal surfaces thereon substantially at right angles to each other, said cutting elements during said movement simultaneously removing two slab portions of the log and two boards therefrom along two pairs of parallel planes with the planes of one pair extending substantially at right angles to the planes of the other pair, whereby the boards are formed with substantially parallel opposite faces.
 25. The method as claimed in claim 24 in which the log with the two flat surfaces formed thereon is moved past a second set of cutting elements arranged to cut two longitudinal flat surfaces thereon substantially at right angles to each other and to the two first-cut surfaces, said second set of cutting elements during said second movement removing remaining slab portions of the log and boards therefrom along parallel planes, whereby the last-mentioned boards are formed with substantially parallel opposite faces.
 26. The method as claimed in claim 25 in which the log after passing the first set of cutting elements is turned over and placed on a suitable conveyor, and the second two flat surfaces are formed along an upper surface thereof, resulting in a squared timber.
 27. The method as claimed in claim 25 in which the log after passing the first set of cutting elements is turned over and placed on a suitable conveyor, the second two flat surfaces are formed along an upper surface thereof, resulting in a squared timber, and each of said planes extends at substantially 45* to the horizontal.
 28. The method as claimed in claim 25 in which all of the slab portions of the log are removed by said cutting elements as pulp chips. 